The invention relates to a removal aid according to the preamble of claim 1 and the use thereof.
The invention more particularly relates to the separation of two materials adhering to one another, whereof one material is sheet or film-like and which are superimposed in the vicinity of a contact surface, such as is e.g. the case with plasters or labels, which are supplied with protective films for contact adhesive layers.
Hereinafter, the surfaces of the carrier material and the substrate are referred to as contact surfaces, which are portions of a carrier material or substrate surface. In addition, the term "substrate" is used both for substrate portions and parts and for the substrate itself.
Therefore the present invention relates to all combinations having a substrate/covering film combination at least as a subcombination.
The detachment or peeling off of a covering material layer or a covering film from a substrate e.g. having an adhesive layer in particular causes problems if the substrate is less flexible or roughly as flexible as the covering film and more especially if the substrate surface covered by the covering film and which is unprotected following the peeling off thereof has to be protected against contamination or damage during the removal of the peel-off film. A reason for protecting the substrate contact surface by a covering film can be e.g. the maintaining of its natural tackiness, its sensitivity to mechanical damage, or the sealing thereof e.g. against the escape of volatile components of the substrate. Conventionally the carrier material, usually a film, adheres by adhesive forces to the substrate, which can be overcome by removal.
The detachment of the carrier material is often problematical and leads to damage to the substrate contact surface to be protected if e.g. by means of a fingernail, knife or other instrument an attempt is made to remove from the substrate the carrier material parts remaining thereon. This procedure is in particular unsuccessful if the ratio of the rigidity of the substrate to the carrier material is unfavourable, e.g. if the carrier material is much more flexible than the substrate and also tears easily, or if a very soft substrate contact surface is to be protected.
This procedure is in particular impossible if it is necessary to avoid damage to the substrate contact surface through contact, e.g. in the case of sterile surfaces of bandages, the control layers of therapeutic plasters (e.g. of the type used for transfer of medicament active substances by skin contact) or surfaces having reactive materials.
For solving this problem it has already been proposed to provide linear cuts or predetermined breaking lines in the carrier material, whereby by removing or bending the carrier material it is possible to detach carrier material portions from the substrate.
However, hitherto by means of these known solutions it has not been possible to obtain a complete and easy exposure of the substrate, particularly if it is a relatively inflexible, sensitive substrate, such as a therapeutic plaster or e.g. a shaped plastic part and a very flexible carrier film, such as a thin aluminium foil or laminate or a polymer film. Particularly in the case of small substrate surfaces, it is difficult to completely expose them. The selective removal of individual substrate portions from a carrier material is also problematical.
The provision of curved cuts or predetermined breaking lines in the carrier film was described in U.S. Pat. No. 3,230,649 and on bending the material leads to the formation of a gripping portion for a part of the carrier material. However, the residue (13) still has to be removed by means of the fingernail or an auxiliary tool from the substrate. As yet no satisfactory process has been provided for the complete undamaged removal of the substrate from the carrier material. In the case of several substrate portions on the same carrier material, it is also possible for a type of peel-off band to interconnect the surfaces of several substrate portions, so that by pulling on a projecting part of the band, the substrate portions linked by it can be drawn off in a single operation from the carrier material. However, prior to the use of the substrate portions they must be separated from the peel-off band. Apart from the relatively complicated manufacture of this known arrangement, it only makes it possible to simultaneously detach several substrate portions and is restricted to small substrate portions. The insertion of strips or threads between the carrier material and substrate, said strips or threads projecting beyond the edge of the substrate portions, also represents an aid for detaching the substrate portions, but involves complicated technology.
All these proposals fail to bring about a satisfactory, problem-free detachment of the substrate from the carrier whilst to a minimum extent in paring the substrate, or otherwise complicated measures are required such as the provision of gripping strips.
The problem of the present invention is therefore to provide an aid for the removal of substrates from the carrier material not suffering from the disadvantage of the prior art. This problem is surprisingly solved by the features of claim 1. Advantageous further developments of the inventive principle can be gathered from the subclaims.
Due to the fact that, according to the invention, in each carrier material contact portion there is a separate, non-linear cutting or predetermined breaking line (i.e. line of weakness), when pressure is applied to the free carrier material surface in the vicinity of the contact surface it is possible to bend a part of the substrate from the contact surface plane, so that a substrate gripping portion is detached for the complete removal of the substrate. This permits a complete detachment or peeling-off of the substrate.
The carrier material and/or substrate can be in the form of more than one layer and different materials and if e.g. the substrate is a therapeutic plaster, the substrate contact surface layer need not be made from the same material throughout.
The materials usable for this purpose must be flexible in the case of the carrier material, whereas in the case of the substrate they can also be rigid. Thus, the substrate can be constituted by shaped plastic members, such as "self-adhering" emblems, Coats of Arm, etc. After removing the substrate from the carrier material a substrate layer surface is freed, which can e.g. be finished in contact adhesive manner and/or which is also permeable to active substances, such as medicaments, such as e.g. the skin contact layer of therapeutic plasters which does not necessarily have to be contact adhesive. In the latter case the carrier material serves as a barrier, which prevents the undesired diffusing of active substances out of a flat therapeutic system. It is also not necessary for the contact surface to be planar and can be shaped in accordance with the intended use of the substrate.
The production of predetermined breaking or cutting lines (lines of weakness) in the carrier material takes place by per se known processes and e.g. for producing cuts punching, cutting, squeezing or stamping the carrier material is preferred. However, it is also possible to cut by laser or high frequency. Predetermined breaking lines can also be produced by punching, perforating, local chemical or heat treatment and particularly in the case of polymer carrier materials by laser cutting etc., as is known to the relevant Expert. The lines can obviously be produced before or after applying the substrate or substrates.